Prostate cancer is currently the most common cancer diagnosed and ranks second after lung cancer as the underlying cause of death among men in the United States. Current concerns about the control of prostate cancer have been directed toward early detection and intervention. Since 1987, the measurement of serum prostate-specific antigen (PSA) has led to dramatic increases in the detection of prostate cancer, presumably at earlier stages and at younger ages. Recent work has suggested that the measurement of different molecular forms of serum PSA in the peripheral circulation, or correcting PSA values for patient age, may enhance its diagnostic characteristics, however, most of our knowledge of these markers is based on Caucasian populations. Whereas the incidence and mortality rates of prostate cancer are significantly higher among African Americans than North American whites, it is currently unknown how serum PSA should be used in African-American men. It is our hypothesis that age-specific reference ranges and molecular forms of PSA will be similar in North American African Americans and whites (null hypothesis). To test this a random sample of approximately 500 healthy African-American men, 40-79 years of age inclusive, residing in Genesee County, Michigan, will be asked to participate in a cross-sectional, community-based study that will determine appropriate reference ranges for serum prostate-specific antigen (PSA). The age-specific distribution of free and complexed PSA, and PSA density (PSA/prostatic volume) will be assessed. Each subject will be evaluated for obstructive urinary tract symptoms, and examined by digital rectal (DRE) and transrectal ultrasonography (TRUS). Prior to the scheduled clinical examination, an interview will be conducted in the home of each participant using a standardized pre-tested questionnaire that will gather information on possible risk factors for prostate cancer and benign prostatic hyperplasia (BPH). At the time of the clinical examination, additional blood samples will be obtained and prepared for frozen storage in anticipation of future epidemiologic investigations. These studies will establish how serum PSA, new molecular forms of PSA, and PSA density should be interpreted in African Americans.